A new perspective on cardiovascular function and dysfunction during endurance exercise: identifying the primary cause of cardiovascular risk.

Exercise mechanical efficiency typically falls within the range of approximately 20 to 25%. This means that a great part of the metabolic energy converted to generate movement is released as heat. Therefore, the rise in core temperature during endurance exercise in humans is proportional to generated work. Cutaneous vasodilation occurs when the core temperature threshold is reached. The rise in heart rate in response to thermal stress is a cardiovascular response that increases cardiac output and skin blood flow. The cardiovascular response during endurance exercise is a complex phenomenon potentially influenced by the involvement of nitric oxide in active thermoregulatory vasodilation. Excessive exercise can create high oxidative stress by disrupting the balance between free radicals' production and scavenging, resulting in impaired cardiovascular function. The above considerations are related to the severity and duration of endurance exercise. The first focus of this narrative review is to provide an updated understanding of cardiovascular function during endurance exercise. We aim to explore the potential role of oxidative stress in causing cardiovascular dysfunction during endurance exercise from a fresh perspective. Additionally, we aim to identify the primary factors contributing to cardiovascular risk during strenuous prolonged exercise by highlighting recent progress in this area, which may shed light on previously unexplained physiological responses. To ascertain the effect of endurance exercise on cardiovascular function and dysfunction, a narrative review of the literature was undertaken using PubMed, ScienceDirect, Medline, Google Scholar, and Scopus. The review highlighted that high oxidative stress (due to high levels of catecholamines, shear stress, immune system activation, and renal dysfunction) leads to a rise in platelet aggregation during endurance exercise. Importantly, we clearly revealed for the first time that endothelial damage, vasoconstriction, and blood coagulation (inducing thrombosis) are potentially the primary factors of cardiovascular dysfunction and myocardial infarction during and/or following endurance exercise.

Mental health, eating habits and physical activity levels of elite Iranian athletes during the COVID-19 pandemic.

BACKGROUND: The COVID-19 pandemic has changed life styles of millions of people worldwide. This study investigated changes in the health, physical activity levels and eating habits of elite athletes during the COVID-19 pandemic lockdown in Iran. METHODS: 383 (248 female and 135 male) elite athletes (168.82 ± 0.07 cm; 63.92 ± 7.42 kg; the body mass index (BMI): 22.3 ± 0.78 kg/m2) participated in this study. The International Physical Activity Questionnaire (IPAQ), Depression Anxiety Stress Scales (DASS-21) and the Impact of Event Scale-Revised (IES-R) study tools were used to measure levels of physical activity and mental health status, respectively. The Emotional Eater Questionnaire (EEQ) was used to assess food consumption related to emotion. Pearson and Spearman correlation analysis test were used in data analysis. RESULTS: Levels of depression and stress were mild and moderate, while levels of anxiety were severe and very severe in most elite athletes. There were levels of low emotional eating by elite athletes during the COVID-19 pandemic. Physical activity levels were negatively correlated with psychological mood measures (p≤0.05), while there were positive correlations between emotional eating behaviours and psychological mood measures (moderate correlation; p≤0.01) and light physical activity levels (weak correlation; p≤0.05). CONCLUSION: This study provides the first preliminary evidence showing that the COVID-19 lockdown conditions negatively influenced the eating habits and levels of physical activity and mental health in elite athletes. Regular high intensity physical activity as health strategy in elite athletes and the general population remains a strategy to improve overall health during the COVID-19 pandemic. Additionally, these findings suggest the need to devise strategies to improve the life styles of elite athletes during pandemics such as the Covid-19 pandemic.

CONTEXTE: La pandémie de COVID-19 a changé les modes de vie de millions de personnes dans le monde. Cette étude a examiné certains indicateurs de bonne santé, les niveaux d'activité physique et les habitudes alimentaires d'athlètes Elite iraniens pendant le confinement lié à la pandémie de COVID-19.Méthodes : 383 (248 femmes et 135 hommes) athlètes élites (168,82 ± 0,07 cm ; 63,92 ± 7,42 kg ; indice de masse corporelle (IMC) : 22,3 ± 0,78 kg/m2) ont participé à cette étude. Le questionnaire international sur l'activité physique (IPAQ), l'échelle DASS-21 (Depression Anxiety Stress Scales) et les scores de l'auto-questionnaire Impact of Event Scale-Revised (IES-R) ont été utilisés pour mesurer les niveaux respectifs d'activité physique et de l'état de santé mentale. L'Emotional Eater Questionnaire (EEQ) a été utilisé pour évaluer les altérations de la prise alimentaire liées à l'émotion. Le test d'analyse de corrélation de Pearson et Spearman a été utilisé pour l'analyse des données.Résultats : Les niveaux de dépression et de stress étaient légers et modérés, tandis que les niveaux d'anxiété étaient sévères à très sévères chez la plupart des athlètes élites. Il y avait des niveaux de faible alimentation d'origine émotionnelle chez ces athlètes pendant la pandémie de COVID-19. Les niveaux d'activité physique étaient corrélés négativement avec les mesures de l'humeur psychologique (p≤0,05), tandis qu'il y avait des corrélations positives entre les comportements alimentaires émotionnels et les mesures de l'humeur psychologique (corrélation modérée ; p≤0,01) et les niveaux d'activité physique légère (faible corrélation ; p≤0,05). CONCLUSION: Cette étude apporte une preuve préliminaire que les conditions de confinement liées au COVID-19 ont influencé négativement les habitudes alimentaires et les niveaux d'activité physique et de santé mentale chez des athlètes élites. L'activité physique régulière à haute intensité aussi bien chez les athlètes élites que pour la population générale reste une stratégie pour améliorer la santé globale pendant la pandémie de COVID-19. De plus, ces résultats suggèrent la nécessité de concevoir des stratégies pour améliorer les styles de vie des athlètes élites lors de pandémies, telles que celle de Covid-19.

Large-scale sporting events during the COVID-19 pandemic: insights from the FIFA World Cup 2022 in Qatar with an analysis of patterns of COVID-19 metrics.

The 2022 FIFA World Cup (FIFA-WC) held in Qatar presented unique challenges, given the potential for rapid transmission of coronavirus disease 2019 (COVID-19) among over 1.4 million international fans attending the event. This study aimed to investigate the impact of the FIFA-WC 2022 on COVID-19 cases, deaths, and reproduction rate (R0) in Qatar. Additionally, it sought to understand the implications of hosting large-scale events during a pandemic without COVID-19 restrictive measures, providing critical insights for future decision-making. Data from "Our World in Data" were analysed for three distinct periods: one week before the FIFA-WC (week-preWC), the four weeks of the event (week-1WC to week-4WC), and one week after (week-postWC). The results revealed a significant increase in COVID-19 cases during week-3WC and week-4WC (compared to week-preWC) in Qatar, followed by a subsequent decrease during the week-postWC. Notably, Qatar experienced a more pronounced surge in positive cases than the global trend. Regarding COVID-19-related deaths, Qatar's peak occurred during week-2WC, while globally deaths peaked from week-3WC to week-postWC. Nevertheless, Qatar's death toll remained relatively low compared to the global trend throughout the event. The findings highlight that the FIFA-WC 2022 in Qatar demonstrated the feasibility of organizing large-scale sporting events during a pandemic with appropriate measures in place. They emphasize the importance of high vaccination coverage, continuous monitoring, and effective collaboration between event organizers, healthcare authorities, and governments. As such, the event serves as a valuable model for future gatherings, underlining the significance of evidence-based decision-making and comprehensive public health preparedness.

FIFA World Cup 2022: What can we learn from the inspiring Tokyo 2020 Olympic Games held in COVID-19 times?

Preparation for the FIFA World Cup 2022 (WC2022) comes in the time of the COVID-19 pandemic. This study aims were to (i) provide a brief overview of the 2020 Tokyo Olympic and Paralympic games in the context of the COVID-19 pandemic, and (ii) highlight the potential challenges and opportunities central to the hosting of the FIFA WC2022. The organisation, public health policies and prevention protocols of the postponed 2020 Olympic/Paralympic Games (Tokyo July-August 2021), the infection rates during the event, as well as the upcoming WC2022 and its related preparations and challenges, were analysed. An unparalleled International Olympic Committee (IOC) effort, together with the Japanese government and people's perseverance and drive, enabled the safe delivery of the Tokyo Olympic/Paralympic Games, which left a legacy beyond sport. This has been aided by the collection of critical data and lessons learnt throughout the games. The stringent public health policies and especially the tight bubble system for players and their respective delegations have certainly been the key components that ensured the successful containment of COVID-19 within the targeted population. One of the most significant lessons learned from the Tokyo 2020 Olympics is the improvement made in controlling COVID-19 in the context of mass gathering events. Strict infection control strategies to prevent future COVID-19 transmission during the FIFA World Cup 2022 are an immediate priority in Qatar and are constantly being prepared. The planned measures and health care strategies appear to be well adjusted to the risk, especially for the large anticipated number of visitors, and can provide sufficient guarantees to conduct relatively "safe" mega sports events.

The effect of music on short-term exercise performance during the different menstrual cycle phases in female handball players.

The present study aimed to evaluate the effect of music on short-term exercise performance during the different menstrual cycle phases (MCP). In different MCP (i.e. menstrual phase (MP), luteal phase (LP), follicular phase (FP)) and in a randomized order, fourteen female handball players aged between 21-24 years performed during music (fast-tempo, 140 bpm) and no-music conditions the following tests: squat jump (SJ) test, countermovement jump (CMJ), agility T-test (TT), and repeated sprint ability (RSA). The profile of mood states (POMS) questionnaire was completed in the different MCP. The rating of perceived exertion was recorded at the end of TT and RSA. MCP does not affect the SJ, CMJ, TT and RSA performance. However, anxiety, anger, and confusion were higher in MP compared to LP and FP. Music enhances the SJ performance during the different MCP. However, the music improved the SJ performance (the first test) only following warm-up in all MCP. In conclusion, listening to music during warm-up could be beneficial for short-term exercise performance in all MCP, but the potential effect of the music on physical performance vanishes over time.

Does wet-cupping therapy improve repeated sprint ability, perceived wellness, and rating of perceived exertion in young active males?

Wet-cupping therapy (WCT) is one of the oldest known medical techniques, used as a traditional and complementary therapy with a wide application all around the world for general health. Research on the effects of WCT on sports performance are sparse and inconsistent. Thus, we aimed to explore the effects of WCT on repeated sprint ability, wellness, and exertion in young active males. Forty-nine active adult males (age: [28 â€‹± â€‹5] years; body height [177 â€‹± â€‹8] cm; body mass: [79 â€‹± â€‹7] kg; body mass index: [25.4 â€‹± â€‹1.8] kg/m2) were selected for the study. The participants performed a running-based sprint test on two separate occasions (Control and Post-WCT). WCT was performed 24 â€‹h before the testing session. They completed the Hooper questionnaire to assess their well-being ( i.e. , sleep, stress, fatigue, and soreness) before each session. The rating of perceived exertion (RPE) was collected after each testing session. A higher maximum power (p â€‹< â€‹0.05, effect size [ES] â€‹= â€‹0.6), mean power (p â€‹< â€‹0.01, ES â€‹= â€‹0.5) and minimum power (p â€‹< â€‹0.01, ES â€‹= â€‹0.6) were recorded post-WCT as compared to Control session along with a better perceived sleep (p â€‹< â€‹0.01, ES â€‹= â€‹0.85). Perceived stress (p â€‹< â€‹0.01, ES â€‹= â€‹0.6) and RPE (p â€‹< â€‹0.001; ES â€‹= â€‹1.1) were lower during the post-WCT compared to the Control session. The present findings demonstrated that WCT moderately enhanced repeated sprint ability and had positive effects on perceived sleep, stress, and exertion. WCT may be an effective ergogenic aid to improve repeated sprint ability and general well-being in young adult males. Future large-scale multicentric clinical studies are paramount to confirm the results of our study.

Can melatonin reduce the severity of post-COVID-19 syndrome?

This short review aimed at (i) providing an update on the health benefits associated with melatonin supplementation, while (ii) considering future potential research directions concerning melatonin supplementation use relative to Coronavirus disease of 2019 (COVID-19). A narrative review of the literature was undertaken to ascertain the effect of exogenous melatonin administration on humans. Night-time melatonin administration has a positive impact on human physiology and mental health. Indeed, melatonin (i) modulates the circadian components of the sleep-wake cycle; (ii) improves sleep efficiency and mood status; (iii) improves insulin sensitivity; and (iv) reduces inflammatory markers and oxidative stress. Melatonin has also remarkable neuroprotective and cardioprotective effects and may therefore prevent deterioration caused by COVID-19. We suggest that melatonin could be used as a potential therapy in the post-COVID-19 syndrome, and therefore call for action the research community to investigate on the potential use of exogenous melatonin to enhance the quality of life in patients with post-COVID-19 syndrome. See also Figure 1(Fig. 1).

Effects of cardiorespiratory rehabilitation program on submaximal exercise in patients with long-COVID-19 conditions: a systematic review of randomized controlled trials and recommendations for future studies.

INTRODUCTION: Long-COVID-19 patients (LC19Ps) often experience cardiovascular and respiratory complications. Cardiorespiratory rehabilitation programs (CRRPs) have emerged as promising interventions to enhance exercise capacity in this population. This systematic review aimed to assess the impact of CRRPs on submaximal exercise performance, specifically the 6-minute walk test (6MWT) outcomes, in LC19Ps through an analysis of available randomized controlled trials (RCTs). METHODS: A systematic search was conducted in PubMed/Medline and Scopus to identify relevant RCTs. Six RCTs meeting inclusion criteria were included in this review, investigating the effects of CRRPs on 6MWT outcomes in LC19Ps. RESULTS: The findings from the included RCTs provide compelling evidence supporting the effectiveness of CRRPs in improving submaximal exercise performance in LC19Ps. These results underscore the potential of CRRPs to enhance submaximal exercise capacity and overall functional well-being in this population. However, future research is imperative to determine optimal CRRPs, including duration, intensity, and specific intervention components. Additionally, the long-term sustainability and durability of CRRP-induced improvements warrant further exploration. Future studies should prioritize patient-centric outcomes and address potential implementation barriers. CONCLUSION: CRRPs show promise in ameliorating submaximal exercise performance among LC19Ps. Further research is needed to refine these programs and ensure their lasting impact on this patient group. SYSTEMATIC REVIEW REGISTRATION: https://doi.org/10.17605/OSF.IO/HMN38. [Figure: see text].

The Effect of Daytime Ingestion of Melatonin on Thyroid Hormones Responses to Acute Submaximal Exercise in Healthy Active Males: A Pilot Study.

It is well known that exercise increases the activity of thyroid glands and raises the blood level of melatonin. The increase of melatonin during exercise may be linked to a rise in thyroid-stimulating hormone (TSH). No previous study has investigated the combined effects of melatonin ingestion and acute submaximal exercise on thyroid hormones' responses. The purpose of this pilot study was to explore the effects of daytime ingestion of melatonin on thyroid hormones' responses to acute submaximal exercise. After 50 min of either melatonin (6 mg) or placebo ingestion, eight physical education students (mean ± standard deviation of age: 22 ± 1 years) were asked to run for 45 min at 60% of their maximum aerobic speed. Free thyroxine (fT4) and TSH were measured in plasma samples before and immediately after exercise. After submaximal exercise, TSH increased by 54% in both placebo and melatonin conditions. There was no significant (Condition × Exercise) interaction, and no significant condition effect for TSH. The fT4 remained unchanged before/after submaximal exercise in both placebo [15.2 (1.9) and 15.0 (1.6) pmol/L, respectively, p > .05], and melatonin [16.7 (2.7) and 16.3 (2.7) pmol/L, respectively, p > .05] conditions. There was no significant (Condition × Exercise) interaction, no significant exercise effect, and no significant condition effect for fT4. To conclude, acute melatonin ingestion did not affect thyroid hormones' responses to submaximal exercise.

Age and clinical signs as predictors of COVID-19 symptoms and cycle threshold value.

Many COVID-19 infected people remain asymptomatic, and hence the diagnosis at first presentation remains a challenge. Assessment at a presentation in primary care settings is usually done by visual triaging and basic clinical examination. This retrospective study involved investigating the medical e-records of COVID-19 positive patients who presented to a COVID-19 centre in Qatar for July 2020. The presence (symptomatic group) or the absence (asymptomatic group) of symptoms along with objective vital examination (ie; heart-rate (HR), temperature, haemoglobin saturation (SpO2)) were analysed and linked to the viral load (ie; cycle threshold (Ct)) of COVID-19 positive patients. Four hundred eighty-one symptomatic (230 males) and 216 asymptomatic (101 males) patients were included. Compared to the asymptomatic male group, the symptomatic male group was older, had lower Ct value and SpO2, and higher temperature and HR. Compared to the females asymptomatic group, the symptomatic females group had lower Ct value, and higher temperature. Compared to the asymptomatic group, the symptomatic group had lower Ct value and SpO2, and higher temperature and HR. Compared to the asymptomatic group, the symptomatic group had lower Ct values (age groups [21-30], [31-40], [41-50] and [51-60]), higher temperature (age groups [21-30] and [31-40], Ct ranges [20.01-25.00] and [25.01-30.00]), higher HR (age groups [21-30] and [31-40], Ct range [15.01-20.00]); and lower SpO2 (age groups [41-50] and [51-60], Ct ranges [15.01-20.00] and [35.01-40.00]). Compared with asymptomatic patients, symptomatic patients with COVID-19 are most likely to be febrile, tachycardic, hypoxic and having higher viral load. Higher viral load was associated with higher HR, higher temperature, lower SpO2, but there was no relation between viral load and age.

Effects of eight weeks of mat pilates training on selected hematological parameters and plasma volume variations in healthy active women.

AIM: To evaluate the effects of eight weeks of mat Pilates training on selected hematological parameters, i.e. white blood cell, neutrophils, monocyte, lymphocyte, hematocrit, hemoglobin as well as plasma volume variations in healthy, active women. METHODS: Twenty-eight women physical education students volunteered to participate in the present investigation. They were assigned to two groups: a Pilates training group (n = 14) that followed an 8-week Pilates training program, and a control group (n = 14). Blood samples were collected at rest at two separate occasions before and after Pilates training. RESULTS: The Pilates training group had higher values of plasma volume variations and lower values of white blood cell (19.4%), neutrophils (32%), hematocrit (4.3%) and hemoglobin (4.6%) compared to control group (p<0.05). CONCLUSION: The results of the present study suggested that Pilates training could be an effective strategy for increasing plasma volume variations and boosting immune system in healthy active women.

COVID-19 lockdown: Impairments of objective measurements of selected physical activity, cardiorespiratory and sleep parameters in trained fitness coaches.

The COVID-19 outbreak resulted in the shutdown of athletic training facilities. Although the effects of these restrictions on daily activity and sleep patterns have been widely analyzed, the employed tools often lacked accuracy, and were based on subjective measures. This study assessed the effects of home confinement on objective physical activity (PA), physiological and sleep parameters in active individuals. Sixteen male elite fitness coaches (age: 29±3 years; height: 183±6 cm; body mass: 82±5 kg, body mass index: 24.7±1.8 kg/m2) participated in this retrospective study. One-way analysis of variance was conducted to analyze selected PA, physiological and sleep parameters collected by smartwatch (Garmin Fenix 6 pro, USA) data during four consecutive months [i.e., pre-confinement, 1st and 2nd months of confinement, and post-confinement, year 2020]. Ramadan intermittent fasting (RIF) month occurred during the 2nd month of confinement. Compared to pre-confinement, significant changes were registered for almost all parameters during the 1st and/or the 2nd month of confinements (p<0.001), with (i) higher values for resting heart rate, sleep latency, and total, light and rapid eye movements sleep times (% change=7-523 %), and (ii) lower values for PA parameters, calories/day spent, average and highest respiratory rates, and deep sleep time during the home confinement period (% change=5-36 %). During the post-confinement month, all parameters regained pre-confinement values. In conclusion, home confinement-induced detraining negatively influenced the objective measurements of cardiorespiratory and sleep parameters among fitness coaches with a deeper effect during the 2nd month of home confinement, possibly due to the effect of RIF.

Is there a diurnal variation of COVID-19 patients warranting presentation to the health centre? A chronobiological observational cross-sectional study.

BACKGROUND: The circadian clock regulates the function of the immune system, the replication of viruses, and the magnitude of infections. The aim of this study was to analyse whether hospital attendance in Coronavirus disease 2019 (COVID-19) patients presents a diurnal variation. METHODS: Data from the electronic medical records of 1094 COVID-19 patients who presented to a Health Centre in Qatar during the month of July 2020 was retrospectively analysed. The following demographic (i.e. time of day (TOD), sex, age), clinical (i.e. cycle threshold (CT), temperature, oxy-haemoglobin saturation and resting heart-rate), biochemical (i.e. uraemia, glycaemia and albuminia) and haematological (i.e. leukocytes, erythrocytes ad platelets) parameters were collected. RESULTS: Univariate analysis showed a significant effect of TOD on hospital admission (p < 0.001), with patients attending the health care centre more during the active behavioural phase (08h00-00h00) compared to the resting phase (00h00-08h00). COVID-19 infection blunted the circadian rhythms of core body temperature, neutrophils and leukocytes family and shifted the circadian rhythms of resting heart-rate and uraemia. Correlation analysis showed a near perfect negative correlation between the age of patients and the TOD (r=-0.97), with older patients attending the care centre earlier during the day. CONCLUSION: COVID-19 infection affected the circadian rhythms of the host through disrupting the circadian rhythms of core temperature and innate immunity mediators. Old patients attend the health care centre earlier compared to younger ones. However, CT during polymerase chain reaction-test was unaffected by the TOD, which limits the conclusion that COVID-19 viral infection exhibits diurnal variation.

A new perspective on cardiovascular drift during prolonged exercise.

Prolonged exercise induces cardiovascular drift, which is characterized by decreasing mean arterial pressure (MAP), stroke volume and heart rate increase. Cardiovascular drift has been debated for a long time. Although the exact mechanisms underlying cardiovascular drift are still unknown, two theories have been proposed. The first is that increased skin blood flow displaces blood volume from central circulation to the periphery, which reduces stroke volume. According to this theory, the rise in heart rate is presumably responding to the drop in stroke volume and MAP. The alternative theory is that an increase in heart rate is due to an increase in sympathetic nervous activity causing reducing time at diastole, and therefore stroke volume. It may be difficult to determine a single robust factor accounting for cardiovascular drift, due to the broad range of circumstances. The primary focus of this review is to elucidate our understanding of cardiovascular drift during prolonged exercise through nitric oxide and force-frequency relationship. We highlight for the very first time that cardiovascular drift (in some conditions and within a specific time period) may be considered as a protective strategy against potential damage that could be induced by the intense and prolonged contraction of the myocardium.

Listening to motivational music during warming-up attenuates the negative effects of partial sleep deprivation on cognitive and short-term maximal performance: Effect of time of day.

This study assessed the effect of time of day (TOD) and listening to music during warm-up on cognitive and physical performances after partial sleep deprivation (PSD) and normal sleep nights (NSN). In a randomized order, twelve male physical education students [mean (SD) age 20.3 ± 2.0 y; BMI 22.90 ± 3.57 kg/m2)] completed a 30-s Wingate test (i.e., mean (MP) and peak powers (PP)), simple (SRT) and choice reaction times (CRT), a mental rotation test (MRT) and a selective attention test. Measurements were performed at 07:00 h and 17:00 h after a NSN and PSD with and without music, with an in-between recovery period of ≥72. Salivary cortisol was measured before and immediately after the Wingate test. Compared to NSN, the results showed that PSD decreased PP (p < .05, d = 0.86) and MP (p < .01, d = 0.86) in the afternoon. However, compared to NSN, listening to music during the warm up after PSD enhanced PP (p < .01, d = 1.40) and MP (p < .05, d = 0.82) in the morning and PP (p < .05, d = 0.78) in the afternoon. Moreover, listening to music lowered post-exercise cortisol in the morning both after NSN (p < .05, d = 0.79) and PSD (p < .05, d = 0.11). After PSD, music reduced the negative mood states (p < .01, d = 0.94), the SRT (p < .05, d = 0.79) and the CRT (p < .05, d = 0.49) in the afternoon. These findings suggest that listening to music during warm-up (i) enhances cognitive and short-term all out performances after NSN and PSD and (ii) partially counteracts sleep-loss-induced degradation of physical and cognitive performances at both TODs.

The effect of Ramadan fasting on the morning-evening difference in team-handball-related short-term maximal physical performances in elite female team-handball players.

The combined effect of Ramadan fasting and the time of theday on the physical performance of team-handball players has not yet been fully investigated. This study investigated the effects of Ramadan fasting on the morning-evening difference in team-handball-related short-term maximal physical performance. With acounterbalanced study design, 15 elite female team-handball players underwent the hand grip (HG), ball throwing velocity (BTV), modified agility T-test (MAT), and repeated shuttle-sprint and jump ability (RSSJA) tests at 07:00 h and 17:00 h, one week before Ramadan (BR), and during thesecond (SWR) and fourth week of Ramadan (4WR). The oral temperature (OT) was monitored prior to exercise and the ratings of perceived exertion (RPE) scale were obtained after RSSJA. The results showed that the time of theday had an effect on OT under all conditions. The HG, BTV, and MAT test performances were higher in the evening than in the morning BR (P< .001, P< .05, and P< .001, respectively). However, the diurnal variation noted in the HG and MAT tests was reversed during the SWR and 4WR, while the BTV variation was blunted during the SWR and reversed during the 4WR. The best RSSJA performance was observed in the evening BR. However, for the best and mean sprint times, areversal of this diurnal variation was observed, which was blunted for the mean jump height and sprint time decrement during Ramadan. Moreover, RPE were influenced by the time of theday and the month of Ramadan. These findings suggest that the diurnal variation of team-handball-related short-term maximal physical performance may be reversed and/or blunted during Ramadan fasting.

Biological Responses to Short-Term Maximal Exercise in Male Police Officers.

The specifics of short-term physical exercise are similar to the immediate reaction demands placed on police officers. Identifying the physiological predisposition to short-term high-intensity exercise in male law enforcement officers will assist in understanding their metabolism and make a significant contribution to a much more personal and individualized workout program. This will improve physical fitness of individual officers, improving their preparedness for such times of emergency. This cross-sectional study was conducted to investigate the responses of hematological (erythrocytes, hemoglobin, hematocrit, leucocytes, monocytes, neutrophils, lymphocytes), hormonal (testosterone, cortisol, melatonin), biochemical (glucose, uric-acid, lactate, creatine-phosphokinase) data to short-term maximal exercise in male police officers (n = 20). Blood samples were collected before- and after- the running-based anaerobic sprint test (RAST), and biological values were corrected for fluid shifts. Data were mean ± standard deviation of differences (= after minus before RAST). After the RAST, values of cortisol, lactate, neutrophils, lymphocytes, and monocytes increased significantly by 7.01 ± 37.36 mmol/l, 7.55 ± 1.67 mmol/l, 0.17 ± 0.26 103/µl, 0.61 ± 0.28 103/µl, and 0.10 ± 0.13 103/µl, respectively. After the RAST, values of melatonin, uric-acid, creatine-phosphokinase, hemoglobin, and hematocrit decreased significantly by -13.24 ± 4.60 pg/ml, -13.28 ± 14.35 µmol/l, -10.23 ± 10.13 IU/l, -2.01 ± 0.81 g/dl, and -4.46 ± 0.59%, respectively. Biological data of male police officers were affected by sprint test. Understanding changes in biological data following short-term maximal exercise can further assist in a better understanding of anaerobic metabolism, which will be helpful to find available methods for coaches to quantify training loads.

The effect of diurnal variation on the performance of exhaustive continuous and alternated-intensity cycling exercises.

The purpose of this study was to explore the effect of time of day (TD) on two types of exercise protocols [continuous (CP) versus alternated (AP)]. Eleven physical education students (mean ± SD: age = 24.4 ± 1.2 years, aerobic peak power (APP) = 290 ± 31.9 W) underwent four sessions. These sessions were performed at 08:00 (AM) and 18:00 (PM) and consisted of cycling exercises until voluntary exhaustion at 90% APP (CP) or 70%-105% APP (AP) with the order of testing randomly assigned. Time to exhaustion (time limit = Tlim) was measured from the start of the test to when voluntary exhaustion occurred. Heart rate (HR) was recorded at baseline (HRbaseline) and throughout the protocols to determine HR at exhaustion (HRpeak). Blood lactate ([La]) was measured at rest, immediately after exhaustion and at 2min30 post-exercise to determine [La]peak. A significantly higher means of Tlim (334 ± 57 s; 272 ± 59 s; p< 0.05), HRbaseline (72 ± 5 beats/min; 67 ± 5 beats/min; p< 0.01), HRpeak (186 ± 8 beats/min; 178 ± 9 beats/min; p< 0.01) and [La]peak (16.2 ± 2.1 mmol/l; 13.9 ± 1.9 mmol/l; p< 0.05) were observed in CP at the PM compared to the AM. In addition, a significant higher means of Tlim (380 ± 54 s; 312 ± 82 s; p< 0.05), HRbaseline (73.1 ± 5.5 beats/min; 67 ± 5.4 beats/min; p< 0.01), HRpeak (186 ± 8 beats/min; 180 ± 9 beats/min; p< 0.05) and [La]peak (17.9 ± 1.8 mmol/l; 14.7 ± 2.1 mmol/l; p< 0.01) were observed in AP at the PM compared to the AM. It is concluded that AP and CP are more appropriate in the late afternoon than in the morning for performing long-lasting exercises. The AP could be a novel strategy for increasing the engagement in physical activity.